System for controlling the sublimation of reactants

ABSTRACT

An apparatus and method improves heating of a solid precursor inside a sublimation vessel. In one embodiment, inert, thermally conductive elements are interspersed among units of solid precursor. For example the thermally conductive elements can comprise a powder, beads, rods, fibers, etc. In one arrangement, microwave energy can directly heat the thermally conductive elements.

REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority benefit under 35U.S.C. §119(e) of Provisional Application No. 60/389,528, filed on Jun.17, 2002. The present application is also related to ProvisionalApplication No. 60/400,210, filed on Jul. 30, 2002, and U.S. applicationSer. No. ______, filed on ______, 2003, entitled “An ImprovedSublimation Bed Employing Carrier Gas Guidance Structures,” which claimspriority from Provisional Application No. 60/400,210.

FILED OF THE INVENTION

[0002] The present invention is related to solid precursor sources usedfor the deposition of thin films on substrates. More specifically, thepresent invention is related to the enhancement of thermal conductivityto the solid precursor inside the precursor source apparatus.

BACKGROUND AND SUMMARY OF THE INVENTION

[0003] Quite often solid precursors are used for vapor reactants,because liquid or gaseous precursors for a certain element may not bereadily available or do not exist at all. Such solid precursors areuseful in a variety of contexts, including, without limitation, atomiclayer deposition (ALD) and other semiconductor fabrication processes.However, it is more difficult to use solid precursors than liquid andgaseous precursors.

[0004] Basically, the handling of solid precursors seems to bestraightforward. Solid precursor is loaded into a container that isheated to a sufficiently high temperature. The precursor sublimes andthe precursor vapor is conducted to a reaction space where it is usedfor the deposition of thin film on the substrate surface.

[0005] Precursor powder generally has rather poor thermal conductivity.The thermal conductivity of the precursor bulk may be low and/or theremay be empty voids between the precursor particles with little contactsurface between the particles, which is undesirable for the conductionof heat energy through the precursor. The volume of the voids depends onthe packing density of the precursor powder. At low pressures, heattransport by convection is also generally inefficient, especially whenthe precursor volume consists of very small voids between the precursorparticles. Heat transport by radiation is also generally inefficientbecause the temperature differences are relatively small and theradiation view factor (line-of-sight paths available for radiantheating) for the bulk of the powder is essentially zero.

[0006] When the precursor vessel is heated from outside, the precursormay have a sufficiently high temperature near the vessel walls while thecenter parts of the precursor powder are insufficiently heated. Thistemperature differential results from the long period of time requiredto heat the centrally located portions of the precursor powder in theprecursor vessel. In addition, sublimation of the non-centrally locatedprecursor consumes thermal energy, further contributing to the center ofthe precursor powder volume remaining at a lower temperature than thepowder proximate the vessel surfaces throughout the process. During ALDpulsing, this temperature differential can cause the solid source todemonstrate a poor recovery rate after using the precursor source for anextended period, because it becomes more and more difficult to reach anequilibrium state in the gas phase of the precursor vessel. Although ALDprocesses are relatively insensitive to small drifts in pulseconcentration, significant decreases in the recovery rate can causeproblems, such as less than full surface coverage of a semiconductorWafer (or other substrate) with the precursor molecules.

[0007] Temperature differences inside the precursor vessel lead to thesublimation of the precursor into the gas phase in hotter parts of thevessel volume and to the condensation of the precursor back to the solidphase in cooler parts of the vessel volume. Often the top surface of theprecursor seems to be cooler than the rest of the precursor. It has beenobserved that a hard and dense crust forms over the surface of theheated precursor over time, causing a pulse concentration drift in theprocess employing the vapor reactant (e.g. ALD). The crust limits thediffusion of precursor molecules from the bulk material to the surfaceand eventually into the gas phase. The result is a decrease in theobserved sublimation rate of the precursor. Initially, the solidprecursor source works well but later it is difficult to get a highenough flux of precursor molecules from the source into the reactionchamber, despite the fact that a significant amount of solid precursorremains in the precursor vessel.

[0008] Another consideration in sublimation vessel design is thatprolonged presence of heated corrosive precursors places heavy demandson those materials in contact with precursors in the precursor vessel.

[0009] The preferred embodiments of the invention provide means forimproving the uniformity of the source temperature in the whole solidprecursor vessel volume. In accordance with one aspect of the presentinvention, inert materials that have high thermal conductivity are mixedwith the solid precursor to improve the thermal conductivity through theprecursor. For example, the inert materials can comprise particles,fibers, rods, or other elements with high thermal conductivitydistributed through the precursor vessel and intermixed with precursorpowder.

[0010] In accordance with one embodiment of the invention, a method ofproducing a vapor from a solid precursor for processing a substrate isprovided, including placing solid units of precursor into a vessel andinterspersing a thermally conductive material through the precursor. Thethermally conductive material thereby preferably serves to conduct heatenergy throughout the units of precursor. A vapor is then formed throughapplying heat energy to both the thermally conductive material and thesolid units of precursor. In one embodiment, after vapor formation, thevapor is routed from the vessel to a reaction chamber and reacted todeposit a layer on a substrate.

[0011] In accordance with another embodiment, a substrate processingsystem is provided for forming a vapor from a solid precursor bydistributing heat throughout the precursor. The provided systemcomprises a heat conducting vessel configured to hold units of solidprecursor, thermally conductive elements being interspersed with theunits of solid precursor. A heater is also provided for heating both theprecursor and the thermally conductive elements.

[0012] In accordance with yet another embodiment, a substrate processingsystem for forming a vapor from a solid precursor is provided. Thesystem includes a vessel configured to hold units of solid precursor anda microwave generator adjacent to the vessel. The generator isconfigured to transmit heat energy in the form of microwave energy toeffectuate the heating of the precursor.

[0013] In accordance with a further embodiment, a mixture for producinga vapor used in substrate processing is provided. The mixture includes abatch of precursor for producing a substrate processing vapor and aplurality of heat transmitting solid forms interspersed through thebatch of precursor. The plurality of heat transmitting solid formscollectively increase the thermal conductivity of the batch ofprecursor.

[0014] Advantageously, implementation of the preferred embodimentsdecreases crust formation at the precursor surface and enhances thesublimation of the precursor. In addition, improving sublimation rateuniformity over the operational life of the precursor batch decreasesthe amount of unused precursor. Refilling of the precursor vessel isalso needed less often due to more efficient material utilization.Another benefit of the present invention is the improvement of the thinfilm thickness uniformity on substrates by processes employing vaporfrom the solid precursor by encouraging rapid recovery of the partialpressure of reactant in the gas phase of the vessel to a steady-statevalue (one such value is P⁰, the saturation vapor pressure of thematerial) from pulse-to-pulse.

[0015] For purposes of summarizing the invention and the advantagesachieved over the prior art, certain objects and advantages of theinvention have been described herein above. Of course, it is to beunderstood that not necessarily all such objects or advantages may beachieved in accordance with any particular embodiment of the invention.Thus, for example, those skilled in the art will recognize that theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

[0016] All of these embodiments are intended to be within the scope ofthe invention herein disclosed. These and other embodiments of thepresent invention will become readily apparent to those skilled in theart from the following detailed description of the preferred embodimentshaving reference to the attached figures, the invention not beinglimited to any particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1A is a schematic overview of a precursor source apparatusinline between a gas source and a reaction chamber.

[0018]FIG. 1B is a schematic side view of the precursor source apparatusof FIG. 1A, constructed in accordance with a preferred embodiment.

[0019]FIG. 2 is a schematic, partially cut-away perspective view of theprecursor source apparatus of FIG. 1B, showing a precursor vessel insidea pressure chamber.

[0020]FIG. 3 is a schematic side view of a precursor vessel from theprior art with crust formation at the upper surface of a volume of solidprecursor, with arrows showing the direction of heat flow.

[0021]FIG. 4 is a schematic top view of a vessel insert with thermallyconductive rods attached to a vessel base, constructed in accordancewith a preferred embodiment.

[0022]FIG. 5 is a schematic perspective view of the insert of FIG. 4.

[0023]FIG. 6 is a schematic side view of a precursor source apparatushaving thermally conductive units interspersed with the precursor, inaccordance with a preferred embodiment.

[0024]FIG. 7 is a schematic, partially cut-away perspective view of aprecursor source apparatus having an adjacent microwave unit, inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring to FIG. 1A, a precursor source apparatus 5 is showninline between a carrier gas source 4 and a reaction chamber 6configured to accommodate a substrate 8.

[0026]FIG. 1B shows a preferred embodiment of the precursor sourceapparatus 5 for vaporizing a solid precursor, the resulting vapor to beemployed in substrate processing, having a pressure chamber 10, an inlet12, an outlet 14 and, preferably, an over-pressure relief valve 16. Theinlet 12 is preferably attached to a carrier gas source 4 (FIG. 1A) viaa first conduit 2, while the outlet 14 is preferably attached via asecond conduit 3 to the reaction chamber 6 (FIG. 1A).

[0027]FIG. 2 is a schematic, partially cut-away, perspective view of theprecursor source apparatus 5 of FIG. 1, showing an inner precursorvessel or crucible 20 inside the pressure chamber 10. The inner crucible20 located inside the pressure chamber 10 is used as a precursor vessel.The shape and dimensions of the crucible 20 are selected depending onthe volume available inside the temperature-controlled pressure chamber10. The material of the crucible 20 can comprise inert substances, suchas quartz glass or silicon carbide. In addition, a particle filter 22 ispreferably located on top of the crucible 20. In an alternativeembodiment, the particle filter is located on the vessel outlet 14 orsecond conduit 3. Porous crucible walls are employed in certainpreferred embodiments, the walls of the crucible acting as particlefilters as the precursor vapor diffuses through the walls.

[0028]FIG. 3 illustrates crust formation in the prior art, one of theproblems that preferred embodiments of the present invention seek toaddress. FIG. 3 shows a schematic side view of the crucible 20 holding avolume of solid precursor 32. A crust 34 tends to form at the uppersurface of the solid precursor 32, with arrows 36 in FIG. 3 showing thedirection of travel of heat which is applied to the crucible 20.

[0029]FIGS. 4 and 5 show still another preferred embodiment of thepresent invention. An insert 38 is configured to fit within the crucible20 (FIG. 2) or other vessel in which the solid precursor is to be held.The insert 38 is preferably selected to have good heat conductivity. Theinsert 38 includes heat conducting elements 40, here rods, which aremachined and attached to a vessel base 42. Preferably, heat flows alongprimary axis of the the elements 40, then radially outward into thematerial, resulting in the whole precursor volume being heatedefficiently and uniformly. The elements 40 are preferably formed from,for example, SiC of the highest purity and quality, since the elements40 can be cleaned and re-used. In another embodiment, the heatconducting elements are preferably made of the same material as thevessel, e.g., stainless steel. In the illustrated embodiment, theelements are formed from SiC-coated graphite, but in other embodimentsthe elements are uncoated. In yet other embodiments the elements areformed from heat conducting substances other than SiC and graphite.

[0030] In accordance with one preferred embodiment, the insert 38 ofFIGS. 4 and 5 is machined and fitted into the precursor vessel 20.Precursor is then poured into the vessel 20. In accordance with anotherembodiment a precursor vessel 20 is first filled with precursor powder32 and then elements 40, shown in FIGS. 4 and 5 as inert,heat-conducting rods, are pushed through the precursor 32 so that thelower ends of the rods 40 touch the bottom of the precursor vessel 20.In an alternate embodiment, the rods are attached to the base of thesource container 10 and the source container 10 is filled with theprecursor powder 32. In yet other arrangements, rods are each configuredto be inserted independently of one another. Preferably, the selectedrod density is a function of the heat transfer properties of the solid(i.e. a solid which has poor heat transfer desirably is selected to havea higher density to lessen the heat transfer path).

[0031] In accordance with the embodiments shown in FIGS. 4 and 5, therods 40 can be located on the bottom plate 42. Preferably the rods 40are arranged, for example, in a polar coordinate type layout, so thateach unit of the precursor 32 is located within a certain maximumdistance from the rods 40 or the base plate 42. The number of verticalrods 40 attached to a plate depends on the physical properties of theprecursor 32. More rods can be used if the heat transport through theprecursor is very poor.

[0032] In yet other alternate embodiments the thermally conductiveelements interspersed with the precursor units can be formed from fixedelements such as, for example, rods, stacked screens, sieves, coils,plates, etc. These units or elements can include both porous andnonporous structures. Preferably, these fixed units or elements arearranged so as to maximize the total amount of thermally conductivesurfaces in contact with precursor, while allowing vapor diffusion fromthe carrier gas inlet to the outlet. Precursor preferably diffusesthrough the mixture of powder and thermally conductive elements.Preferably, the carrier gas convectively transports the chemical in theupper portion of the vessel (or head space) from the inlet to theoutlet.

[0033]FIG. 6 shows a preferred embodiment in which loose thermallyconductive elements 46 are mixed with precursor powder 32 inside thecrucible 20. In certain preferred arrangements the conductive elements46 are powder particles, while in alternate arrangements the conductiveelements 46 can comprise larger loose elements, such as fibers, pieces,flakes, pellets, spheres, or rings, etc. The chemical catalyst industryuses elements having similar geometry (beads, pellets, spheres, rings,etc), each being coated with a catalytic material, which would alsoprovide appropriate geometric unit configurations in order to practicealternate arrangements of the present invention. These units or elements46 can include both porous and nonporous structures. Preferably, theseloose elements 46 are arranged so as to maximize the total amount ofthermally conductive surfaces in contact with precursor 32. In certainpreferred embodiments the elements 46 are formed from an inert,thermally conductive material, such as a ceramic, e.g., SiC. The shapesand materials from which these elements 46 can be formed is discussed ingreater detail below.

[0034] In an alternate embodiment, a plurality of conductive elements 46are interspersed with a batch of precursor to form a mixture.Preferably, the inclusion of heat transmitting solid forms collectivelyincreases the thermal conductivity of the batch of precursor.

[0035] Referring to FIG. 7, another embodiment of the present inventionis shown employing an energy emitter 48 adjacent to the crucible 20. SiCor another inert, energy-absorbing material (not shown) is placed in theprecursor vessel, preferably in the illustrated vessel or crucible 20along with precursor material, so that the precursor (not shown) is inclose contact with the energy absorbing material. In one arrangement,the precursor vessel is also preferably transparent to the emittedenergy. The wavelength of the emitted energy is preferably in themicrowave range, although alternate arrangements of the embodimentsdisclosed herein employ other wavelengths of emitted energy.

[0036] In a preferred operation, microwaves heat the microwave-absorbingmaterial and heat flows from the heated material, which can be inaccordance with FIGS. 4 and 5 or 6, to the precursor. In otherarrangements, a crucible is employed inside a vessel, the crucibleitself absorbing microwave energy, thereby transmitting heat from thewalls of the crucible to the precursor. Generally precursors that arenormally used for the deposition of thin films do not absorb microwavesand, thus, cannot be directly heated with microwaves. However,substances such as SiC absorb microwaves, allowing SiC to heat uprapidly, thereby effectuating the desired uniform heating of theprecursor. Similarly, other combinations of energy-absorbing materialand energy sources operating at different wavelengths will beappreciated in view of the present disclosure. In still anotherarrangement, when the precursor material is capable of directlyabsorbing electromagnetic energy like microwaves, direct heating of theprecursor material is sufficient to effectuate the desired precursorvaporization, such that separate microwave absorbing material can beomitted.

[0037] In alternate arrangements of the aforementioned embodiments, itshould be understood that it is also possible to omit the inert crucibleand load the precursor directly into the bottom of the pressure chamber10; preferably, the pressure chamber 10 surfaces in contact with theprecursor are sufficiently inert. A particle filter is also preferablyplaced on top of the precursor powder or, in an alternate embodiment, inthe conduit (not shown in figures) between the precursor source andreaction chamber. In embodiments in which a crucible is employed, thecrucible can be formed to have porous walls to serve as a filter,thereby reducing the need for a separate particle filter. In accordancewith one preferred embodiment, heat conducting material is then mixedwith the precursor, while in another preferred embodiment a machinedinsert is placed into the chamber prior to, during, or after loading ofthe precursor into the chamber.

[0038] Size And Shape Of The Inert Heat Conducting Material

[0039] Heat conducting material or thermally conductive elements can beused in different shapes, e.g., powders, fibers, irregular pieces andmachined pieces.

[0040] The grain size of inert powders is selected according to theapplication, as would be appreciated by the skilled artisan. Precursorsource vessels that do not include any particle filters shouldpreferably be filled with conductive, inert elements (e.g., SiC powder)that are coarse enough to prevent the dusting of the material. Precursorsource vessels equipped with a filter can be filled with a wide range ofconductor particle size; preferably the smallest particles are stoppedby the particle filter. One benefit of using small inert, conductiveparticles is that very small voids in the precursor powder can be filledand the packing density and the heat conductivity through the precursorvolume is increased. One goal of certain preferred embodiments is toprovide uniform and high heat conductivity through the precursor powder.

[0041] In accordance with a preferred embodiment, the mixture ofconductive elements and precursor has a heat conductivity lower thanthat of pure conductor material and higher than that of pure precursor.For example, inert heat conducting material is added to the solidprecursor forming a solid mixture, so that there is preferably about10-80% by volume of heat conducting material in the precursor/conductormixture and, more preferably, about 30-60% by volume of heat conductingmaterial in the mixture. Re-use of the conductor, although possible, isa challenge, especially when the particle size of the conductor is verysmall.

[0042] In another embodiment, fibers of inert, conductive material, suchas carbides or carbon, are employed. Fibers preferably conduct heatefficiently along the fibers through the precursor volume and, also,donate heat to the precursor that is located near the fibers. The fibersare preferably cut into pieces that have a length of about 1-20 mm andare mixed with the aforementioned precursor. For example, suitable SiCfibers are sold, e.g., by Reade Advanced Materials, USA. The heatconducting fibers selected preferably distribute heat from the heater orthe precursor vessel walls to the precursor.

[0043] In accordance with yet another embodiment, machined pieces ofinert, conductive material are used, thereby preferably allowing certainbenefits. By employing larger machined pieces, recovery of heatconducting material is relatively easy after use. In addition, the heatconducting material can be cleaned and reused many times. Accordingly,very high purity and expensive heat conducting material can be usedeconomically. Machined pieces can take the form of, for example, rodsand plates (as illustrated in FIGS. 4 and 5), or combinations of thoseshapes and a variety of other shapes, including, for example, screensmounted at various levels along the length of rods or other extensions.

[0044] One embodiment employs a combination of machined pieces andsmaller heat conducting pieces. Machined pieces preferably effectuatelong-distance heat transport from the heater or heated walls of theprecursor vessel deep into the precursor volume, while loose heatconducting units (e.g., beads, powder, fibers, etc.) are preferablymixed with the precursor to effectuate the local distribution of heat tothe precursor. In one arrangement, heat conducting material in the formof powder is employed in combination with heat conducting material inthe form of fibers. In another arrangement, rods are employed inconjunction with a powdered heat conducting material. In view of thedisclosure contained herein, the skilled artisan will readily recognizeother combinations of heat conducting material forms and materials thatwould also be advantageous.

[0045] In selecting the added inert material that is used according tothe present invention, good thermal conductivity is desirable. Inertmaterials for this purpose preferably have a thermal conductivity of atleast about 50 W/m*K, more preferably at least about 80 W/m*K, for theapplications presented in this patent application at room temperature,and most preferably have such high conductivity under the conditions ofuse.

[0046] Silicon Carbide

[0047] Silicon carbide (SiC) is employed in certain preferredembodiments to form the inert material which is added to the crucible orvessel. SiC is an extremely hard material that has high thermalconductivity, negligible vapor pressure and very good resistance againstchemicals at elevated temperatures. According to Performance Materials,Inc., USA, the thermal conductivity of SiC is 250 W/m*K at roomtemperature and about 120 W/m*K at 400° C. A wide range of SiC gradeswith different purities are commercially available. The color of siliconcarbide (SiC) is known to correlate with its purity. According to ReadeAdvanced Materials, USA, black SiC has a purity of up to about 99.2%,dark green SiC has a purity of about 99.5% and the purity of light greenSiC is about 99.7%. SiC is available in the form of powder, grit,crystals, granules, wafers, fibers, platelets, bars and arbitrary formpieces. Typical impurities in SiC that is produced from silica sand andcoke are SiO₂, elemental Si, free C, and Fe₂O₃. Preferably, suchimpurities are minimized to decrease potential contamination of theprocess employing the precursor. Accordingly, in a preferred embodiment,the inert conductive material is preferably greater than 99% pure.

[0048] A number of commercial sources of high purity SiC exist. Forexample, SiC of 99% purity is available from Atlantic EquipmentEngineers, USA, in all grit sizes. Poco Graphite, Inc., USA, alsoproduces very high purity SiC with a Chemical Vapour Infiltration (CVI)method where pure graphite is contacted with silicon monoxide (SiO)vapor (Eq. 1). The amount of impurities in SiC is in the ppm level.

SiO(g)+2C→SiC+CO(g)   Eq. 1

[0049] Cerac, Inc., USA, sells vacuum deposition grade (99.5%) SiCpieces that have dimensions in the range of 3-12 mm.

[0050] Other Materials

[0051] A number of other suitable inert carbides are commerciallyavailable. The thermal conductivity of transition metal carbides istypically about 50% lower than the thermal conductivity of SiC; theconductivity of transitions metal carbides will often be sufficient toprovide improved sublimation. Atlantic Equipment Engineers, USA, sellspowders of tungsten carbide (WC), vanadium carbide (VC), tantalumcarbide (TaC), zirconium carbide (ZrC), hafnium carbide (HfC),molybdenum carbide (MoC), niobium carbide (NbC) and titanium carbide(TiC). The purity of the carbide powder is typically 99.8-99.9%. Suchmetal carbides may also have useful metal-carbon stoichiometries otherthan 1:1.

[0052] In addition, alternate carbides, such as boron carbides (e.g.,B₄C) that have sufficiently high thermal conductivity can also beemployed; boron carbides are preferably not used for applications thatare sensitive to boron impurities.

[0053] Another suitably inert and conductive material is PocoFoam™,manufactured by Poco Graphite, USA, which is very light carbon foam andhas a thermal conductivity in the 100 to 150 W/m*K range.

[0054] Coated Materials

[0055] In selecting a material from which to form the heat conductingmaterial, it is undesirable to utilize materials that have high heatconductivity but have a property that, unmodified, prevents the directuse of the material in solid precursor vessels. For example, a potentialmaterial may have a desirable thermal conductivity, but the materialreacts with the precursor during processing, i.e., during sublimation.Therefore, the material which is chosen to directly contact theprecursor is preferably inert. Certain preferred embodiments allow theuse of material that if used alone would be undesirable, by coating anon-inert material having a high thermal conductivity with an inertsubstance. For example, both graphite and silicon are good conductors ofheat. Graphite is very soft and easily forms solid particles that maycontaminate substrates in a reaction chamber. A hard inert coating isthus preferably formed on the graphite surface to decrease the number ofparticles released from the graphite. Similarly, silicon is an efficientreducing agent if the native oxide on the silicon surface is broken. Aninert coating deposited on the silicon surface preferably prevents thereactions between the silicon and precursors.

[0056] In particular, graphite or silicon can, in certain preferredembodiments, be coated with SiC. Other suitable coating materials areboron carbides, niobium carbide (NbC), tantalum carbide (TaC), titaniumcarbide (TiC), tungsten carbide (WC), zirconium carbide (ZrC),molybdenum carbide (MoC), vanadium carbide (VC) and hafnium carbide(HfC). Such metal carbides may also have useful stoichiometries otherthan 1:1. In one embodiment, insufficiently pure carbides are preferablycoated with a thin, high-purity CVD carbide film that prevents thecontamination of the precursor in the precursor vessel. In thisembodiment, impurities of the CVD carbide coatings are in the parts permillion (ppm) range and, thus, do not significantly contaminateprecursors or substrates. Transition metal nitrides, such as niobiumnitride (NbN), tantalum nitride (TaN), titanium nitride (TiN), tungstennitride (WN), zirconium nitride (ZrN), molybdenum nitride (MoN),vanadium nitride (VN) and hafnium nitride (HfN), serve as furtherexamples of suitable inert coatings on heat conducting materials. Inaddition, in one embodiment, silicon nitride is formed on the siliconsurface and, thus, silicon parts and pieces are passivated.

[0057] The following examples, including the methods performed andresults achieved are provided for illustrative purposes only and are notto be construed as limiting upon the present invention.

EXAMPLES Example 1

[0058] A Pulsar® 3000 ALCVD™ reactor, available commercially from ASMInternational, N.V. of Bilthoven, The Netherlands, was used for thedeposition of HfO₂ from alternating pulses of HfCl₄ and H₂O viasequential, self-saturating surface reactions. The HfCl₄ vapor for thosepulses was provided from a solid source. A mixture of 157.6 g of HfCl₄and 200.8 g of 99.5% SiC (obtained from Orkla Exolon, Norway) was loadedinto a source container. In the mixture there was approximately 100 cm³of each precursor. Thus, the mixture of precursor material andconductive elements was a 1:1 volumetric mixture.

[0059] As a result, the source temperature could be lowered from200-205° C. (no carbide fill) to 180° C. (with carbide fill). It isbelieved that the recovery rate (i.e., time after pulsing thatsufficient vapor develops for the next pulse) of the source improvedbecause of the increased and more stable sublimation rate of theprecursor. The deposition of thin films from the same precursor batchwas made possible for a longer time than without the carbide fill. Theaddition of SiC improved the HfO₂ thin film thickness uniformity on thesubstrates. Use of SiC conductive filler did not affect the number ofparticles on wafers.

Example 2

[0060] ZrCl₄ powder was mixed with boron carbide (B₄C) powder in a glovebox. The mixture was loaded into a source boat made of glass. The sourceboat with the mixture was then placed in a glass tube to serve as acarrier tube. Ends of the tube were covered with Parafilm to prevent theexposure of ZrCl₄ to room air and moisture. The tube was carried fromthe glove box to an F120 ALD reactor from ASM International N.V., andthe source boat was moved from the carrier tube to a source tube(pressure vessel) of the reactor while inert nitrogen gas was flowingout of the source tube. After the loading of the source boat wascompleted and substrates were placed into the reaction chamber of thereactor, the reactor was evacuated to vacuum with a mechanical vacuumpump. Pressure of the reactor was adjusted to about 3-10 mbar withflowing inert nitrogen gas. The reaction chamber was heated to thedeposition temperature and the ZrCl₄ reactant zone of the reactor washeated also to the sublimation temperature. ZrO₂ thin film was depositedfrom sequential alternating pulses of ZrCl₄ and H₂O vapor. It was foundthat the sublimation rate of ZrCl₄ increased clearly when boron carbidehad been mixed with ZrCl₄. Boron carbide helped to transport heat energythrough the precursor volume.

[0061] Although this invention has been disclosed in the context ofcertain preferred embodiments and examples, it will be understood bythose skilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications thereof. Thus, itis intended that the scope of the present invention herein disclosedshould not be limited by the particular disclosed embodiments describedabove, but should be determined only by a fair reading of the claimsthat follow.

We claim:
 1. A method of producing a vapor from a solid precursor forprocessing a substrate, comprising: placing solid units of precursorinto a vessel; interspersing a thermally conductive material with theunits of precursor; forming a vapor through applying heat energy to boththe thermally conductive material and the solid units of precursor; androuting the vapor from the vessel to a reaction chamber.
 2. The methodof claim 1, further comprising reacting the vapor to deposit a layer ona substrate.
 3. The method of claim 1, wherein interspersing thethermally conductive material with the solid units of precursorcomprises forming a solid mixture having about 10% to 80% by volume ofthermally conductive material in the mixture.
 4. The method of claim 1,wherein the interspersing the thermally conductive material with thesolid units of precursor comprises forming a solid mixture having about30-60% by volume of thermally conductive material in the mixture.
 5. Asubstrate processing system for forming a vapor from a solid precursorby distributing heat to the precursor, comprising: a vessel configuredto hold units of solid precursor; a plurality of thermally conductiveelements interspersed with the units of solid precursor; and a heaterbeing configured to transmit heat energy to both the thermallyconductive elements and the precursor.
 6. The system of claim 5, whereinthe vessel is a heat conducting vessel.
 7. The system of claim 5,further including a reaction chamber fluidly coupled to the vessel, thechamber being configured to provide a suitable environment for thereaction of a vapor, originating from the vessel, to deposit a layer ona substrate.
 8. The system of claim 7, wherein the reaction chamber is achemical vapor deposition chamber (CVD).
 9. The system of claim 7,wherein the reaction chamber is an atomic layer deposition chamber(ALD).
 10. The system of claim 5, wherein the units of solid precursorare in powder form.
 11. The system of claim 5, wherein the thermallyconductive elements are formed from a substance which is substantiallyinert to reactions within the vessel.
 12. The system of claim 5, whereinthe thermally conductive elements have a coating which is substantiallyinert to reactions within the vessel.
 13. The system of claim 5, furtherincluding a vacuum chamber surrounding the vessel.
 14. The system ofclaim 5, wherein the heater is a microwave generator configured totransmit microwave energy to the thermally conductive elements.
 15. Thesystem of claim 5, wherein the thermally conductive elements are rodsconfigured to be inserted within the vessel.
 16. The system of claim 15,wherein the rods are attached to a base plate configured to be insertedinto the vessel.
 17. The system of claim 15, wherein the rods areattached to a vessel base.
 18. The system of claim 15, wherein the rodsare each configured to be inserted independently of one another.
 19. Thesystem of claim 5, wherein the thermally conductive elements are fibersconfigured interspersed with the units of solid precursor containedwithin the vessel.
 20. The system of claim 5, wherein the thermallyconductive elements are in powder form.
 21. The system of claim 5,wherein the thermally conductive elements comprise carbon.
 22. Thesystem of claim 21, wherein the thermally conductive elements comprisemetal carbide.
 23. The system of claim 21, wherein the thermallyconductive elements comprise transition metal carbide.
 24. The system ofclaim 21, wherein the thermally conductive elements comprise boroncarbide.
 25. The system of claim 21, wherein the thermally conductiveelements comprise silicon carbide (SiC).
 26. The system of claim 5,wherein the thermally conductive elements comprise a combination of rodsand powder.
 27. The system of claim 5, wherein the thermally conductiveelements comprise a combination of rods and fibers.
 28. The system ofclaim 5, wherein the thermally conductive elements have a thermalconductivity of at least about 50 W/m*K at room temperature.
 29. Thesystem of claim 5, wherein the thermally conductive elements have athermal conductivity of at least about 80 W/m*K at room temperature. 30.A substrate processing system for forming a vapor from a solid precursorcomprising: a vessel configured to hold units of solid precursor; and amicrowave generator adjacent to the vessel, the generator beingconfigured to transmit heat energy in the form of microwave energy toeffectuate the heating of the precursor.
 31. The system of claim 30,further comprising a plurality of thermally conductive elementsinterspersed with the units of solid precursor, the thermally conductiveelements readily absorbing the microwave energy.
 32. The system of claim30, wherein the units of solid precursor are formulated to be directlyheated by the microwave energy transmitted from the microwave generator.33. The system of claim 30, wherein the vessel is formulated to bedirectly heated by the microwave energy transmitted from the microwavegenerator.
 34. A mixture for producing a vapor used in substrateprocessing comprising: a batch of precursor for producing a substrateprocessing vapor; and a plurality of heat transmitting solid formsinterspersed through the batch of precursor, the plurality of heattransmitting solid forms collectively increasing the thermalconductivity of the batch of precursor.
 35. The mixture of claim 34,wherein the shape of the plurality of heat transmitting solid forms isselected from a group consisting of powder, spheres, irregularly shapedpieces, and machined pieces.
 36. The mixture of claim 34, wherein theshape of the plurality of heat transmitting solid forms is selected froma group consisting of rods, screens, sieves, coils, and plates.
 37. Themixture of claim 34, wherein, the plurality of heat transmitting solidforms are formed from a material selected from a group consisting ofmetal carbide, transition metal carbide, boron carbide, and siliconcarbide.
 38. The mixture of claim 34, wherein the plurality of heattransmitting solid forms are substantially inert with respect to desiredreactions employed in the substrate processing.
 39. The mixture of claim34, wherein the plurality of heat transmitting solid forms are coatedwith a substantially inert material with respect to desired reactionsemployed in the substrate processing.
 40. The mixture of claim 34,wherein the plurality of heat transmitting solid forms are configured toconduct heat from the precursor proximate to edges of the precursorbatch to precursor substantially centrally located within the precursorbatch.
 41. The mixture of claim 34, wherein the plurality of heattransmitting solid forms absorb microwave energy originating from amicrowave generator and release heat to the solid precursor.